Trailing 14-10 in the fourth quarter, Williams mounted a 13-play, 87-yard drive - the Toreros' longest of the game - capping it with a 7-yard pass to Campano for the win. Williams was 16 of 27 for 202 yards and an interception.
Williams put San Diego (7-1, 5-1 Pioneer) on the board with a 35-yard TD pass to Brandon White in the second quarter. David Long kicked a 50-yard field goal in the third quarter, and San Diego outgained Drake 271-204.
San Diego's victory ends the Bulldogs' streak of 19-straight home conference game wins, with the last loss coming in 2009.